list_element_type_not_assignable

The element type '{0}' can't be assigned to the list type '{1}'.

The analyzer produces this diagnostic when the type of an element in a list literal isn't assignable to the element type of the list.

The following code produces this diagnostic because 2.5 is a double, and the list can hold only integers:

List<int> x = [1, 2.5, 3];

If you intended to add a different object to the list, then replace the element with an expression that computes the intended object:

List<int> x = [1, 2, 3];

If the object shouldn't be in the list, then remove the element:

List<int> x = [1, 3];

If the object being computed is correct, then widen the element type of the list to allow all of the different types of objects it needs to contain:

List<num> x = [1, 2.5, 3];

Unless stated otherwise, the documentation on this site reflects Dart 3.7.3. Page last updated on 2025-05-08. View source or report an issue.